In 2008, the NIDDK initiated the Assessment, Serial Evaluation, and Subsequent Sequelae of Acute Kidney Injury (ASSESS-AKI) Study which is prospectively enrolling adults and children with and without acute kidney injury (AKI) at Participating Clinical Centers (PCC). The goals of the study are to define the natural history of AKI; to evaluate the impact of the presence and severity of AKI on renal, cardiovascular and other clinical and patient-centered outcomes; and to identify predictors of adverse events after an episode of AKI. The ASSESS- AKI PCCs represent a broad spectrum of clinical settings ranging from cardiothoracic surgery to intensive care units to general hospital floors in a geographically diverse research consortium. The proposed ASSESS-AKI- Phase 2 will extend follow-up through September 30, 2018. It will offer a unique opportunity to leverage the existing effort and success of ASSESS-AKI-Phase 1 through long-term prospective follow-up of a matched cohort of participants with and without initial AKI for a variety of clinical outcomes that will support addressing novel scientific goals. The enclosed application is in response to RFA-DK-12-509, Limited Competition for the Continuation of the Assessment, Serial Evaluation, and Subsequent Sequelae of Acute Kidney Injury (ASSESS-AKI) Study (U01), on behalf of the Kaiser Permanente Northern California/University of California, San Francisco PCC. The six Specific Aims to be addressed by the participating PCC sites and Data Coordinating Center are: Aim 1) To re-enroll a high percentage of ASSESS-AKI participants into Phase 2; Aim 2) To maintain outstanding levels of retention, data quality and outcome ascertainment among ASSESS-AKI participants; Aim 3) To evaluate the association between AKI and markers of cardiac ischemia, fibrosis, and endothelial dysfunction as potential contributors to excess cardiovascular risk in patients with AKI; Aim 4) To examine the impact of AKI on the future development of metabolic disturbances among ASSESS-AKI participants; Aim 5) To employ unbiased proteomic techniques to identify novel urinary protein biomarkers at 3 months after an episode of transient AKI that identify patients at risk for progressive renal dysfunction; and Aim 6) To promote and support the conduct of ancillary studies in ASSESS-AKI, including collaboration with the broader nephrology research community. Through the ongoing participation of the PCCs, ASSESS-AKI-Phase 2 will become an unparalleled resource that will expand the science related to AKI natural history as well as the impact of AKI on the development and progression of CKD, cardiovascular disease, survival, quality of life, functional status and other important outcomes.